Cream the softened butter and powdered sugar together until smooth and combined but not aerated.

Beat in the egg until fully incorporated.

Add the flour and salt and mix until a soft dough forms. Don't overmix.

Shape into a disc, wrap tightly, and refrigerate for at least 1 hour.

Roll the dough out to 3-4 mm thick and fit it into a 9-10 inch tart pan with a removable bottom. Trim the edges and dock the base with a fork. Chill for at least 20 minutes.

In a medium saucepan, heat the milk and vanilla over medium heat until it just reaches a simmer. Don't let it boil.

While the milk heats, whisk the egg yolks, sugar, salt, and cornstarch together in a separate bowl until smooth and glossy. Place the bowl on a damp kitchen towel to keep it steady.

Slowly pour the hot milk into the egg mixture in a steady stream, whisking constantly.

Take it off the heat and whisk in the butter until completely combined. For an extra silky texture, push it through a fine mesh sieve.

Pour the custard into a clean bowl. Press plastic wrap directly onto the surface to prevent a skin from forming. Let it cool to room temperature, then refrigerate until completely cold (at least 2 hours).

Give the chilled custard a quick whisk to loosen it, then scoop it into the cooled tart shell. Spread it out evenly with a spoon or offset spatula.

Slice the strawberries and arrange them over the custard. You can fan them in rows, arrange them in concentric circles, or simply pile them on.

If you like, add a few fresh mint leaves for color. Dust with powdered sugar just before serving, or brush the strawberries with a little warmed strawberry jam for a glossy finish.

Chill until ready to serve.